Expression change of P2X_3 receptor in spinal dorsal horn and dorsal root ganglion in inflammatory pain rats / 第三军医大学学报

ABSTRACT

Objective To investigate the expression change of P2X3 receptor in spinal dorsal horn and dorsal root ganglion(DRG) in rats with experimental inflammatory pain.Methods Totally 30 SD rats received a subcutaneous injection of carrageenan in the right paw to establish inflammatory pain model,and then divided randomly and equally into 5 groups,that is 6,12,24,72 and 168 h after injection.Another 6 rats undergoing a subcutaneous injection of normal saline in the right paw served as control.Pain threshold was assayed by thermal radiation and von Frey filament in 2,4,6,12,24,72 and 168 h after injection.Expression of P2X3 receptor in spinal dorsal horn and DRG of every group was measured by immunohistochemical staining(IHC).Results After injection of carrageenan,thermal hyperalgesia and mechanical allodynia appeared in the rats.The thermal withdrawl latency(TWL) and 50% paw withdrawl threshold(PWT) were decreased obviously from 2 h,descended to the lowest at 12 h,then returned to the normal level after 72 h.The expression of P2X3 receptor in spinal dorsal horn was increased obviously from 24 h,while that at DRG was increased obviously from 12 h.Both of the expressions lasted for 72 h,and returned to the normal level at 168 h after injection.Conclusion Thermal hyperalgesia and mechanical allodynia appear in the rats after carrageenan injection,and the P2X3 receptor is activated and up-regulated in the DRG and spinal cord,suggesting that P2X3 receptor may play an important role in the incidence and development of inflammatory pain.